[Coco] Grr!!! Bad MPI! No biscuit!

[Gene Heskett]

On Monday 07 May 2007, Mike Pepe wrote:
>Gene Heskett wrote:
>> On Saturday 05 May 2007, coco at yourdvd.net wrote:
>>> I believe Marty Goodman once recommended that the ls245 in the CoCo AND
>>> the MPI be replaced with a faster version (the ''F'' version, I think
>>> he mentioned). -r
>>
>> The F version might work, but I think I'd troll the manuals and find one
>> that has a better controlled turnaround behaviour.  The F is a copper
>> plated bottom cast iron power hog, and since it runs from the coco's power
>> supply rather than the mpi's, we don't need to heat that puppy up anymore
>> than we have to.  Its typically 3 degrees from signing a ~30~ now.  I had
>> in mind maybe the 74HCT245, but I'd have to check the books to be sure
>> about that. Speed isn't what we need there, a few ns of tristate time
>> between directions is. IIRC 10ns of tristate time would clean that problem
>> up like a spray of Mr. Clean & a Bounty towel. :)
>
>Gene, if that's really the problem, why don't we engineer a little
>daughter card with a couple of LS241's back-to-back. You could use some
>inverters to add some propagation delays to ease off the timing- using
>two tri-state drivers instead of one integrated one means the timing can
>be tweaked in both directions.

My giddyup got up and left.

>> OTOH, the next problem is those solder coated edge connectors.  I got
>> tired of messing with those, sawed them off, and spot soldered a gold
>> plated strip I sawed off an old pc video card.  End of that problem. :-)
>
>-Mike
>
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-- 
Cheers, Gene
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